1. Filed of the Invention
The invention relates to a filter and, more particularly, to a filter which does not includes a capacitor, an inductance or a resistor.
2. Description of the Related Art
In evaluation criteria of various electronic devices, to audio/video household electrical appliances such as a personal computer, a television or a stereo, electromagnetic compatibility (EMC) is a key index of quality. In the developed countries nowadays, the evaluation report of the EMC is more and more important. Since the transmitting speed of a signal in the electronic device is faster and faster, the electromagnetic interference (EMI) generated by electronic elements disposed in the electronic device is more and more serious. Thus, the normal operation of the electronic device is affected.
The EMC evaluation includes the electromagnetic interference (EMI) evaluation and the electromagnetic susceptibility (EMS) evaluation. The EMI may be transmitted in a conducting mode and a radiating mode, and the radiated EMI problem should be solved by changing the wiring or the disposing mode of the elements. In the conventional technology, to reduce the affection of the EMI, designers usually add various filters such as a low pass filter, a high pass filter, a π-shaped filter and a band pass filter to reduce the EMI in the circuit.
In an actual architecture, passive elements such as a capacitor, a resistor or an inductor are usually used to form the filter in the conventional technology. However, the capacitor, the resistor and other passive elements not only consume the layout space of the electronic device, but also limit the micromation development of the electronic devices. Thus, how to improve the quality of the electronic device with considering the layout area of the electronic device becomes an important subject on filter design nowadays.